The operation of drawing continuous filaments into a fiber fan, gathering them into a strand, and winding them on bobbins is well known. When glass is used as the raw material the product thus formed, hereinafter referred to as "continuous strands" may be used for widely varying purposes. In the form of fabrics, rovings, or in the form of cut short pieces or staples, the products serve advantageously as an insulating medium or as reinforcing means. Furthermore the continuous strands may be used in the fabrication of a wet fiber mat typified by U.S. Pat. No. 3,766,003. In the plastics industry substantial quantities of continuous strands are used as reinforcement for glass fiber-reinforced plastics.
In order to ensure uniformity of the continuous strand, breakage of the individual continuous filaments must be avoided during the winding operation when the filaments are being drawn about the bobbin. This is difficult to accomplish since even slight variations in homogeneity, fluctuations of temperature during the filament formation or spinning process and the like, may be sufficient to cause the continuous glass filaments, which are relatively delicate, to break. In the production of continuous strands from a continuous glass filament a particular difficulty resides in producing new filaments sufficiently quickly to replace the broken filaments, and in introducing or integrating these newly formed filaments into the continuous strand of filaments being wound on the bobbin. When a continuous filament breaks or is otherwise terminated during the collection of the continuous filaments from the fiber fan into the continuous strand, a new filament is formed at the filament former or bushing by a newly formed drop or bead of glass which drops vertically under the influence of gravity from an orifice at the bushing and pulls the new filament along. The gradual transition from the drop to the new filament has been called a "cone," "needle" or "icicle" and together with the drop constitute the initially formed section of the new filament. The newly formed filament can be integrated into the moving continuous strand only after it has been separated from its associated drop and needle. It is also known that integration also requires that the newly formed filament be predrawn such that its diameter is substantially as fine as the fiber diameter of the other filaments making up the continuous strand.
Known devices for integrating such newly formed filaments include German Pat. No. 1,062,399 and German Pat. No. 1,246,937 which incorporate a V-shaped trough which extends longitudinally underneath the point where the filaments are formed. The V-shaped trough deflects a newly formed filament from the direction of its vertical fall and allows the newly formed filament to be conducted by means of mechanical devices to a joining rotating drawing drum which aids in the joining of the new filament with the continuous strand being formed. The drum separates the new filament from its associated drop and needle, predraws it to a preliminary fiber diameter, draws it into a filament of proper thickness and thereafter conducts the newly formed filament toward the direction of the continuous strand into which it may then be integrated with the help of a mechanical thread guide.
In practice, however, this known apparatus does not always ensure that the drops and needles are safely caught by the rapidly rotating drawing drum. The drops and needles tend to be relatively inflexible and are rarely able to conform to the circumference of the rotating drum and thus tend to rebound from the drum. Additionally, guide and deflector plates which surround the drum and prevent the newly formed filament from being projected in an undesired direction, interfere with and render the transfer of the predrawn filament to its respective place in the continuous strand more difficult. This complicated device suffers from additional disadvantages including high wear of the rotating drawing drum, integrating mechanical thread guide and the rapidly moving mechanical conducting or guiding devices, due to the high abrasiveness of the continuous glass filaments. Furthermore, the rapidly rotating joining drawing drum necessitates high manufacturing standards and needs to be precisely balanced and supported in bearings. Moreover, faultless performance of the device requires constant servicing and lubrication. Thus, the known devices entail high initial capital expenditure and operational costs.
In the production of rayon fibers a plurality of single fibers are drawn parallel to each other from a rapidly rotating drawing drum, lifted or separated from the drum before reaching a complete winding around the surface of the drum and divided into rayon fibers which are then further processed into a flat fiber formation, such as mats or fibrous webs, or into velvety roves or fiber bands. German laid-open Patent Application 1,796,143 teaches that the above-described joining rotating drawing drum and other mechanical parts may be dispensed with in the production of rayon fibers by utilizing water as a guiding medium in order to predraw the filaments and subsequently guide the filaments to a drawing drum.
Apparently this method is feasible in the production of rayon fibers because a rapidly rotating drawing drum is still used such that the individual filaments can run parallel to and separated from each other by a slight distance. Using streams of water allows the individual filaments to be predrawn to a desired preliminary diameter without the combined steps of predrawing and drawing to a final fiber diameter as in the case with the heretofore-described joining drum. Unfortunately, the efficient predrawing device disclosed by German laid-open Patent Application 1,796,134 has not proved adaptable to the integration of newly formed filaments into a continuous strand of glass filaments.